1. Field of the Invention
The present invention relates to a photoelectric conversion device and imaging system.
2. Description of the Related Art
CMOS photoelectric conversion devices can read out signals at high speed with low noise and are used in digital still cameras, digital video cameras, and the like.
Photoelectric conversion devices require higher resolutions to sense images by decreasing the pixel pitch and increasing the pixel count. At the same time, photoelectric conversion devices need to decrease the distance from a microlens to the light receiving surface of a photodiode so that a lens with a larger optical aperture value, that is a smaller F-number, is available even at a smaller pixel pitch.
According to Japanese Patent Laid-Open No. 2005-328066, red (R), green (G), and blue (B) color filters 19 are formed on a fifth insulation film 18 covering a fourth metal interconnection M4 serving as an uppermost metal interconnection, as shown in FIG. 1 of Japanese Patent Laid-Open No. 2005-328066.
FIG. 1 of Japanese Patent Laid-Open No. 2005-328066 shows a structure in which color filters are formed on the insulation film covering the uppermost metal interconnection, without a planarized film. This structure can shorten the distance between the color filter 19 and the light receiving surface of a photodiode 12.
In the structure shown in FIG. 1 of Japanese Patent Laid-Open No. 2005-328066, red (R), green (G), and blue (B) color filters are arranged separately from each other like islands in concave portions of the insulation film. In this case, it is difficult to ensure the contact areas between the color filters and the insulation film. The color filters may readily peel from the insulation film.